Possibly too much air somehow got into the system. If you had work done at at shop, i recommend that you bring it back to them for warranty service. If you choose to work on it yourself search the site for bleeding air from the system, this link is helpful.

Other then excess air in the system, it could be many other parts that are causing overheat. Fan clutch, water pump, etc etc. Spin the fan clutch fan when car is cold, if should have resistance and not spin freely. Check for leaks within the vehicle. Search the site as well, this topic has been covered more times then a pizza with pepperoni.